Container structure and manufacture



April 8, 1969 w. T. SAUNDERS 3,437,228

CONTAINER STRUCTURE AND MANUFACTURE Filed Oct. 14, 1965 Sheet of a FIG.I

. INVENTOR WILLIAM I SAUNDERS BY gww qw ATTORNEYS April 1969 w. T.SAUNDERS 3,437,228

CONTAINER STRUCTURE AND MANUFACTURE Filed Oct. 14, 1965 v Sheet ors FIG.6

m x M60 6 FIG. 7

9| 62 iii l INVENTOR WILLIAM T SAUNDERS ATTORNEYS April 8, 1969 w. T.SAUNDERS CONTAINER STRUCTURE AND MANUFACTURE Shet Filed Oct. 14. 1965 R0 ms MR N U A S .l N M L n w ATTORNEY United States Patent 3,437,228CONTAINER STRUCTURE AND MANUFACTURE William T. Saunders, Weirton, W.Va., assignor to National Steel Corporation, a corporation of DelawareFiled Oct. 14, 1965, Ser. No. 495,796 Int. Cl. B65d 17/24 US. Cl. 220-547 Claims ABSTRACT OF THE DISCLOSURE Process for forming a unitary rivetfor an easy-open container without substantially decreasing thethickness gage of metal confronting container contents in which the headportion of a rivet is clamped between a yieldablymounted, spring-loadedpin and a solidly-mounted punch member during formation of the rivet.Easy-open container utilizing a unitary rivet to hold one end of anelongated tab opener to a container. The elongated tab opener has acurvilinear configuration at its secured end for initiating puncture ofthe container. The container closure has a scoreline which circumscribesand is substantially parallel to such curvilinear configuration of theelongated tab opener. Guide means on the container closure constrainpivotal movement of the elongated tab opener to maintain such parallelrelationship.

This invention is concerned with easy-open containers and teachesmethods for economical fabrication of readily-openable sheet metalcontainers.

Containers with opening keys, or other tools, which have to bemanipulated into working position are known in the container art. Onecontribution of the present invention is a new integral opener which iscarried in working position on a container. In general, manufacture ofintegral openers has been limited to soft, lightweight metals such asaluminum. Also uses for integral openers of the prior art have beenlimited. The integral-opener of the present invention can be fabricatedfrom any of the standard sheet metal container materials, includingsheet steel. Further, the integral opener of the present invention canbe used economically in any environment including applications havinghigh strength requirements, such as carbonated beverage containers.

The present invention is also concerned with manufacture of a novel lugfrom container stock sheet metal. This unitary lug is located to permiteasy removal of a portion of the container using a separate forktypeopener. With the novel methods taught by the present invention thisunitary lug can be fabricated economically from any of the standardsheet metal container materials, including sheet steel.

In particular, the present invention teaches methods for processingsheet metal, such as steel strip, to form container closures usingsimplified steps which can be readily automated for the economicproduction of high strength, easily openable, and low cost containerclosures. Mild steel, plated with a protective metal or unplated, can beused in carrying out the invention since the manufacturing processmaintains the protection aiforded by platings of tin, aluminum,aluminum-manganese, zinc, and the like, usually applied to steel.

A unique fabrication method is taught which does not substantiallydiminish the strength or gage of the sheet metal container material. Asa result, a light gage steel can be used which makes for easier, morefoolproof opening. For example, with the present process a con-3,437,228 Patented Apr. 8, 1969 ice aluminum. The result is a moreeconomical, more readily openable, hand-operable container closure.

While the invention is applicable to a number of container materials,the specific description to follow will emphasize use of steel platesince it has not been considered commercially feasible in the past tomake easy-open container covers for many applications from steel. Thespecific description will also emphasize manufacture of closures forcarbonated beverage containers since the high strength requirements ofbeer cans, for example, present the greatest obstacles to easy-openfeatures desired in hand opening containers. Overcoming the obstacles inthat environment makes it clear that the teachings of the invention canbe applied readily throughout the container market.

In the past, tin-plated steel can ends for beer were made ofphosphorized steel, temper T-6, of a weight of around 100 to 112 poundsper base box, that is steel with a thickness gage around .011" andhigher. With the introduction of lighter gage double-reduced materialsfor can sidewalls, attempts were made to reduce the endwall weight gagebelow 100 pounds per base box. However a relatively heavy weight endwallmaterial was necessary in order to make a strong end seam and in orderto withstand the pressures of pasteurizing beer without outward bucklingof the endwall. Teachings of the present applicant on a reinforcedcountersunk can end in his copending application, Ser. No. 387,609,filed Sept. 5, 1964, which is included herein by reference, permit beercan ends to be manufactured from much lighter tinplate, for example inthe 50 to pound per base box range (around .006) using mild steel.

While the reinforced countersunk method provides greater strength forbeer can ends, it is to be understood that the present invention is notlimited to reinforced countersunk container closures but is applicableas well to other embodiments including two-piece containers using adrawn body in which the opener is part of either the body or the closuremeans. However, the reinforced countersunk method makes possibletinplate beer can ends of a weight less than 75 pounds per base boxwhich greatly reduces the force required to open such a container. Alsothe steel can be universal-temper (TU) mild steel plate withoutadditives as required for phosphorized or renitrogenized steel. By mildsteel is meant the conventional steel used in making blackplate,tinplate, and the like having a carbon content up to about fifteenpoints (015% C.); in brief, one of the conventionally produced steelswithout costly additives can be used to fabricate products taught by thepresent invention.

The invention teaches formation of a rivet for holding an integral tabopener to container plate in which the rivet is unitary with the plate.That is, the rivet is formed from metal in the plate. The invention alsoteaches formation of a flanged lug which is unitary with sheet metalcontainer plate. The important contribution in these teachings is thatfabrication of a unitary rivet or a unitary lug takes place withoutsubstantially decreasing the thickness gage of the head portions ofthose unitary structures which confront the material in the container.

Also, because of a number of unique features in the integral tab opener,its securing means, and coordinated operational features between theseand the area to be removed from a container cover, the manufacturingprocess taught for manufacture of an integral tab opener container canbe straight-forward and sequential without the problem of individualsteps in the manufacturing process doing damage to or impeding workperformed in other steps.

The accompanying drawings will be referred to for a more detailed andspecific description of the above and 3 other unique features of theinvention. In these drawings FIGURES 1 through 4 illustrate steps information of a protrusion and a reinforced countersunk rim in a sheetmetal blank,

FIGURE 5 is a sectional view of a portion of the sheet metal blank ofFIGURE 4 with a tab-opener removably held on the blank.

FIGURE 6 illustrates steps in the formation of a unitary rivet,

FIGURE 7 illustrates a completed unitary rivet securing the tab openerto the sheet metal blank,

FIGURE 8 is a top plan view of a container closure embodying theinvention,

FIGURE 9 is a sectional view along the line 9-9 of FIGURE 8,

FIGURE 10 is a top plan view of a full open container embodying theinvention,

FIGURE 11 illustrates steps in the formation of a unitary lug, and

FIGURE 12 illustrates a completed unitary lug.

Referring to FIGURES 1 through 4, stages are shown in the formation of aprotrusion in sheet metal by drawing of the sheet metal along withsimultaneous formation of a reinforced countersunk periphery. Thedrawing steps gather sufficient metal for formation of a unitary rivetwith little significant change in the gage of the metal forming theprotrusion.

Referring to FIGURE 1 in particular, a button 15 is formed in blank 16with the button 15 protruding from the bottom surface of the blank andforming a depression in the top surface of the blank. It will be notedthat the button 15 is shallow in depth and large in diameter. Thisconfiguration permits sufficient metal to be drawn into the button toenable formation of a unitary rivet without harmful reduction ofthickness gage. At the periphery of blank 16 a countersunk rib 18 isformed.

In FIGURE 2-, folding over of the countersunk rib 18 is shown at 22 andbutton 15 of FIGURE 1 is inverted to form protrusion 24 from the topsurface of the blank 16. It will be noted that the protrusion 24 has anincreased depth and reduced diameter in relation to the button 15 ofFIGURE 1. This working of the metal is accomplished withoutsubstantially reducing the thickness of metal drawn in button 15; inpractice the thickness of the metal in the button 15 is within onethousandth of an inch of the thickness of the metal in the remainder ofthe sheet metal blank.

In the third step shown in FIGURE 3, a hem 26' is formed at theperiphery of blank 16. A protrusion 28 of increased depth and decreaseddiameter with respect to the protrusion 24 of FIGURE 2 is formed bymovement of the metal already drawn into protrusion 24.

In step four, shown in FIGURE 4, the protrusion 30 is formed from metalin the protrusion 28 of FIGURE 3. This protrusion from the top surfaceof the blank is substantially cylindrical in a cross-sectional planewhich is parallel to the sheet metal blank. Endwall 32 closes one end ofthe protrusion and longitudinal axis 34 is substantially perpendicularto the plane of the blank. Sidewall 36 extends substantiallyperpendicularly between endwall 32 and the plane of the blank anddefines opening 40 in the bottom surface of the sheet metal blank. Atthe periphery of blank 16, folds 42. are formed from the metal in hem 26of FIGURE 3.

FIGURES shows a typical cross-sectional configuration of a protrusionbefore formation of a rivet. Protrusion 30 includes endwall and sidewall46. A tab opener 52 is formed with rounded edges curled under as shownat 54 and depressed ledge configuration 55 around aperture 56 formed intht tab opener. Ledge 55 rests on panel 50 of the sheet metal blank. Thecross-sectional configuration of protrusion 30 can also befi'usto-conical if desired. Endwall 45 as shown is slightly convex, butcan be planar, or concave as well.

Tab opener 52 is removably held on the protrusion 30 by aperture 56being placed over the protrusion. The next steps in formation of theunitary rivet are important for maintaining required strength andthickness gage properties. Prior art integral openers formed fromaluminum sheet metal, for example, require relatively heavy gage sheetmetal, around .0145" in thickness, due in part to the prior art methodof forming unitary rivets. In the prior art, a tab opener was secured toa container by forcing metal in the rivet head to overlap the tabopener. This caused a 60 to reduction in thickness gage of the metal inthe rivet head. As a result the rivet head, which faced the containercontents, was often less than .006" in thickness while the remainder ofthe container cover, from which metal had to be torn to make an openingwas a heavy 10145 in thickness. By following the steps of the presentinvention a unitary rivet is formed without decreasing the thicknessgage of the sheet metal in the rivet head facing the container contents;therefore the entire container end from which the protrusion is formedcan be of a lighter gage.

Formation of a unitary rivet in accordance with the teachings of theinvention is shown in FIGURES 6 and 7. Endwall 45 of protrusion 30 isclamped between a yieldably-mounted, spring-loaded movable pin 58 and asolid mounted punch 60. The panel 50 of the sheet metal closure issupported contiguous to protrusion 30 on solid support die 62. Byclamping metal in the endwall 45 between spring loaded pin 58 and solidmounted punch 60 its thickness does not change during formation of arivet. Sidewall 46 is prevented from moving inwardly by spring loadedpin 58. The sidewall moves outwardly as shown in dotted lines in FIGURE6. Spring-loaded pin 58 moves downwardly as the protrusion 30 iscollapsed.

As shown in FIGURE 7, end-wall 45 becomes the head of the unitary rivetformed and sidewall 46 overlaps aperture 56 holding tab opener 42 topanel 50. In this Way a structurally strong rivet is formed and metal inthe rivet head, which faces the container contents and therefore mustwithstand container pressures, is not reduced in thickness duringformation of the rivet. With this method the entire metal blank fromwhich the unitary rivet is formed can be substantially thinner than thatrequired by prior art methods. As a result the container is easier toopen and more economical to manufacture.

FIGURE 8 shows a container closure- 64 with tab opener 52 held to panel50 by unitary rivet 66. Scoreline 68 defines an area 69 to be removed bylifting tab opener 52. Pivotal movement of tab opener '52 about rivet 66in the plane of the sheet metal is constrained by raised guides 70.Constraining pivotal movement of tab opener 52 is important to properpuncturing of the panel 50. Puncturing of panel 50 is facilitated byestablishing a substantially parallel relationship between tab end 71and scoreline 68 Within the sector designated 72. By constrainingpivotal movement of tab opener 52 the substantially parallelrelationship between end 71 and the scoreline is maintained even thoughthe tab opener 52 may be turned slightly for purposes of raising freeend 74 of the tab opener 52, as will be described later. As a result ofthe above described parallel relationship the opening force of tabopener 52 is concentrated most effectively along that portion ofscoreline 68 where initial puncture will occur When opening a container,tab opener 52 acts as a Class 1 lever with its fulcrum at rivet 66, itsoutput or working end at 71, and its input end at 74. Referring toFIGURES 8 and 9, by lifting tab end 74 a lever action, with mechanicaladvantage dependent on the relative lengths of the input and output armson either side of the fulcrum (rivet 66), concentrates a depressingforce at end 71 along the parallel portion of the scoreline 68 'withinsector 72. Guides 70 by constraining pivotal movement of tab opener 52maintain the proper parallel relationship and concentration of downwardforce of the tab opener along the portion of screenline 68 within sector72.

The downward force at end 71 of tab opener 50 is implemented forpurposes of initial opening of a container by a lifting force at the endof the rivet 66 closest end 74. This lifting force places the metal atthe scoreline within sector 72 under tension.

The configuration of scoreline 68 is also important at the end oppositeto sector 72. After lifting tab opener 52 to puncture panel 50, tabopener 52 is pulled backwardly toward the periphery of the can forremoval of defined area 69. The metal tears along the scorelines betweenguides 70. The scoreline terminates in a blunt end having corners ofdiffering radii of curvature. The larger radius of curvature 76 causesthe metal to tear along that part of the scoreline first so that themetal being torn converges on a smaller radius of curvature 77. As aresult the metal to be broken for final removal of defined area 69 isreduced to the small radius of curvature of 77.

With the tab opener 52 secured to the panel 50 and positioned as shownin FIGURE 8, the opener is recessed with relation to the top of theperipheral edge of container cover 64 so that the container will notinadvertently catch on objects during handling or packing. The tabopener 52 can be operated in this position, however the invention makesprovision for raising end 74 to facilitate opening. Referring to FIGURESand 9 it will be seen that the edges of tab opener 52 are rounded andinclude sheet metal which projects downwardly toward panel 50. A raisedridge 91 is provided on panel 50 within the defined area 69. Ridge 91 ispositioned near rivet 66. By pivoting tab opener 52 slightly, adownwardly projecting edge of tab opener 52 rides up on ridge 91 raisingend 74. Raised guides 70 constrain pivotal movement so that thesubstantially parallel relationship between end 71 and a portion ofscoreline 68 within sector 72 is maintained notwithstanding the slightpivoting for purposes of raising tab end 74. It will be obvious thatridge 91 can also be used to constrain pivotal movement of tab opener52.

Tab opener 52 also includes indention 92 at a turned-up portion of thehandle near end 74. This indention facilitates gripping of the handleduring the pulling step in opening a container.

The above teachings provide a readily openable, hand operable device.Instructions for opening a container can be simplified as follows: turn,lift, and pull.

A specific embodiment of the present invention using tin-plated steelfor beer cans would have a panel thickness in the range of .005 to.0075", and residual metal at the scoreline of .002".

The teachings of the present invention are also applicable to a fullopen container. An embodiment of a full open container cover is shown inFIGURE 10. Rivet 80 is placed off-center with respect to container cover82, however other features described above remain substantially thesame, including a parallel relationship at the secured end of the tabopener between tab opener 84 and scoreline 86. It will be noted that thetab opener 84 is positioned entirely within the scoreline so that theblank can be scored afer attaching the tab opener. Scoreline 86 aftercircumscribing tab opener 84 narrows considerably in approaching theperiphery of container cover 82 and proceeds circumferentially aroundthe periphery to approach and terminate contiguous to the scorelinecircumscribing the tab opener. Raised guide portion 88 is extendedaround the container cover to prevent upward bending of the panel or aportion of the panel during tearing of the metal.

There are many applications for easy-open containers where the integralta b type opener is not completely suitable; for example, in vendingmachines of hot products and at commercial establishments which wouldrequire a person to hand open numerous containers. The unitary lug,easy-open container, as described in copending application entitledContainer Lug by Marvin S. Young, filed concurrently with the presentapplication and assigned to the same assignee, is especially adapted tosuch uses. The unitary lug, however, presents difiiculties infabrication, especially when working with steel, which are solved by thepresent invention.

Referring to FIGURE 11, protrusion 90 is formed in a sheet metal blankby a series of steps similar to those described in relation to FIGURES1-4 used in forming a protrusion for a unitary rivet. In general, theunitary lugprotrusion will be longer and sometimes larger than a unitaryrivet protrusion so that more metal should b drawn in the formationsteps in order to avoid harmful reduction of thickness of the metal.

Protrusion 90 includes a closed endwall 92 and a cylindrically shapedsidewall 94 spaced radially from longitudinal axis 96 of the protrusion.

The present invention teaches a method of forming a flanged unitary lugin which the closed endwall 92, forming the head of the lug is notreduced in thickness during formation of the flange. By forming aflanged lug without reducing the thickness of the head of the lug, whichmust withstand pressures of container materials, the entire sheet metalblank can be of lighter gage.

In order to accomplish this result, endwall 92 is clamped between powerpunch 98 and yieldably mounted pin 99. Sheet metal portion 102, adjacentto and surrounding protrusion 90, is rigidly supported by fixed supportdie 104. Yieldably mounted pin 99 will move a predetermined distance outof the aperture formed by protrusion 90 and will then be rigidlysupported.

Force is applied on endwall 92, in a downward direction as indicated, bypunch 98. Pin 99 within the protrusion prevents an inward collapse ofthe sidewall of the protrusion, collapsing the sidewall is initiated atthe rounded portion at the top edge of protrusion 90, and a portion 106of the sidewall flares outwardly forming a shoulder as endwall 92 ismoved downwardly. No outside support die is necessary for the sidewallsince the somewhat beveled edge where the sidewall joins the remainderof the sheet metal blank prevents outward collapse in this region andthe rounded configuration at the top of protrusion 90 initiates theflare out of the sidewall. After pin 99 moves a predetermined distanceout of the aperture as indicated in FIGURE 11, it is rigidly supported,and sidewall portion 106 forms a projecting shoulder or flange onunitary lug 108 as shown in FIGURE 12.

The pin means 99 determines the spacing between flange 106 and adjacentportions of the sheet metal 102; this will ordinarily be between and fora beverage container. The flange will ordinarily extend radiallyoutwardly about beyond the circumference of sidewall 94. The sheet metalis scored as indicated at 110.

By insertion of a pronged pull-type opener between 106 and 102 with aprong on opposite sides of the lug, and by applying an upward force, thescored portion of the sheet blank is torn from the container. The sizeof the lug may vary with the size of the container being opened and theamount of flange and spacing between the flange and the sheet metalcontainer can be determined by the predetermined movement of pin 99.

While several embodiments of the present invention have been shown anddescribed above, it is understood that modifications and substitutionscan be made without departing from the principles of the presentinvention. Therefore it is understood that the scope of the presentinvention is to be determined by the appended claims.

What is claimed is:

1. Hand openable sheet metal container comprising elongated tab openermeans secured at one longitudinal end to one surface of a sheet metalcontainer by unitary rivet means formed from sheet metal of thecontainer,

a scoreline of diminished metal thickness in the sheet metal containerdefining an area to be removed from the container by lifting the tabopener means, the scoreline circumscribing the tab opener means at thelongitudinal end of the tab opener means secured to the sheet metalcontainer, with such longitudinal end of the tab opener means beingaligned with and contiguous to the scoreline such that a lifting forceat the remaining longitudinal end of the tab opener means causespuncture of the container along the aligned portion of the scoreline,

means for constraining pivoting of the tab opener means about theunitary rivet means in a plane substantially parallel to the one surfaceof the container so as to maintain the aligned relationship between theend of the tab opener means secured to the sheet metal container and thecircumscribing scoreline at such end of the tab opener means.

2. The structure of claim 1 in which the one surface of the sheet metalcontainer is an end wall.

3. The structure of claim 1 in which the elongated tab opener means liescompletely within the scoreline defining an area to be removed from thesheet metal container.

4. The structure of claim 1 in which the means for constraining pivotalmovement of the tab opener means comprises raised guide means projectingfrom the one surface of the sheet metal container.

5. Hand-openable sheet metal container cover comprising elongated tabopener means secured at one longitudinal end to one surface of a sheetmetal container cover by unitary rivet means formed from sheet metal ofthe container cover, the elongated tab opener means having a curvilinearconfiguration at the end secured to the sheet metal container cover,

a scoreline of diminished metal thickness in the sheet metal containercover defining an area to be removed from the cover by lifting theelongated tab means, the scoreline circumscribing and being insubstantially parallel relationship to a projection of the curvilinearconfiguration at the end of the elongated tab means secured to the sheetmetal cover, and

raised guide means projecting from the one surface of the sheet metalcover for constraining pivotal movement of the elongated tab means aboutthe unitary rivet means and maintaining the substantial parallelrelationship between the curvilinear end of the elongated tab means andthe circumscribing scoreline at the end of the elongated tab meanssecured to the container cover.

6. The container cover of claim 5 in which the scoreline terminates in ablunt end in spaced relationship from the curvilinear end, with theblunt end having corner portions of differing radii of curvature.

7. Hand-openable metallic container structure comprising a sheet metalblank,

a unitary rivet formed in the sheet metal blank to extend from onesurface of the sheet metal blank,

an elongated tab opener means secured at one longitudinal end to thesheet metal blank by the unitary rivet, the elongated tab opener meanshaving a curvilinear edge at its end secured to the sheet metal blank,

a scoreline of diminished metal thickness in the sheet metal blankdefining an area to be removed by the elongated tab opener means, thescoreline circumscribing a perpendicular projection on the sheet metalblank of the elongated tab opener means at its secured end and beingcontiguous with and substantially parallel to at least a portion of thecurvilinear edge of the elongated tab opener means at its secured end,and

a raised portion of sheet metal projecting from the one surface of thesheet metal blank for constraining pivotal movement of the elongated tabmeans to maintain the substantially parallel relationship of thecurvilinear portion of the elongated tab opener means with the scorelineat the secured end of the elongated tab means; the elongated tab meansconstituting a Class 1 lever for removing the area defined by thescoreline with the unitary rivet acting as a fulcrum for the elongatedtab opener means so that the portion of the curvilinear edge of theelongated tab opener means is forced downwardly to break sheet metal atthe contiguous substantially parallel scoreline by lifting action at theremaining end of the elongated tab opener means longitudinally oppositeto its secured end.

References Cited UNITED STATES PATENTS THERON E. CONDON, PrimaryExaminer.

G. T. HALL, Assistant Examiner.

